Objective:To evaluate the significance of the retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) in the diagnosis and prognosis of visual function of pituitary tumor. Methods:The thickness of RNFL was measured by OCT in 39 patients with pituitary tumor (39 eyes) and 76 normal subjects(76 eyes). Comparisons were made with regard to the RNFL thickness of quadrants and in means between normal and pituitary tumor group. The correlation between mean RNFL thickness and mean defect of visual field. Results:There was significant difference of RNFL thickness in various quadrants and in means between normal and pituitary tumor group (P < 0.000).The mean RNFL thickness was positively correlated with mean defect of visual field (R=0.41,P=0.000). Conclusion:RNFL thickness measured by OCT provides a new method for the diagnosis of pituitary tumor.